The prior art and the first task to be solved by the present invention
Conventionally, as a wire connector, there has been known a relay connector provided with plugs and the like which is described in JP-A-10-12294, for example.
That is, here described is a relay connector having a structure which holds an open state by engaging release buttons 11, 25 with outer peripheral surfaces of base housings 5, 19. However, in the above-mentioned conventional example, it is necessary to form engaging catching portions in the base housings 5, 19 and the structure becomes complicated and, at the same time, the miniaturization of the device becomes difficult.
On the other hand, JP-UM-B-8-2924 discloses a self-locking terminal device as a type of wire connector.
That is, one end portion of a wire Y is clamped and held by bringing a locking portion 13 of a locking spring 2 into pressure contact with a side face portion 17 of a terminal fitting 3. However, in the above-mentioned prior art, along with the miniaturization of the device, a spring force becomes small and hence, a desired holding force is not obtained and the reliability of contact is lowered. To the contrary, when the locking spring 2 has a large width uniformly, it is impossible to obtain the dispersion of stress at a spring portion. Further, since a large notch is formed in a back surface of the terminal fitting 3, a stress is concentrated on the notched portion and hence, there arises a drawback that the strength is remarkably deteriorated.
Further, in the above-mentioned both prior arts, in spite of a fact that the positional relationship between the terminal fitting (leaf spring) and a manipulation part is important, the terminal fitting (leaf spring) and the manipulation part are assembled using the housing as the reference. Accordingly, it is necessary to assemble the terminal fitting and the manipulation part to the housing with high positioning accuracy and hence, there arises a drawback that the assembling cannot be performed easily.
Accordingly, in view of the above tasks, it is a first object of the present invention to provide a small-sized wire connector which has a simple constitution, exhibits the high connection reliability, and ensures the easy assembling.
The prior art and the second task to be solved by the present invention
Further, in the above-mentioned self-locking terminal device described in JP-UM-B-8-2924, the locking spring 2 is resiliently deformed by pushing a manipulation button 4 downwardly using a flat-type driver D thus connecting a wire Y.
However, in the above-mentioned self-locking terminal device, in connecting the wire Y, it is necessary to keep on pushing the locking spring 2 using the manipulation button 4 and hence, the operability is poor. Further, since the above-mentioned locking spring 2 is housed in the inside of an insulating body 1, it is difficult to clearly judge whether the locking spring 2 is in a state that the wire Y can be connected or not.
As means which can solve one of the above-mentioned drawbacks, the relay connector having a locking mechanism described in the above-mentioned JP-A-10-12294 is named.
That is, the relay connector has a structure in which by pushing respective one ends of the release buttons 11, 25 into the base housings 5, 19 and engaging them with each other, it is possible to hold an open state that wires 31 can be inserted into the base housings 5, 19.
However, in the above-mentioned relay connector, when the electric connection is established by inserting the wires 31 into the base housings 5, 19, it is necessary to pick one end portions of the release buttons 11, 25 and to pull out them from the base housings 5, 19. Accordingly, it is impossible to perform all manipulations using a same tool. That is, to pull out the release buttons 11, 25, it is necessary to replace the tool with a different tool thus worsening the operational efficiency.
Further, it is difficult to adjust a force for pulling out the release buttons 11, 25 and hence, there is a possibility that the release buttons 11, 25 are excessively pulled causing the rupture of the release buttons 11, 25.
Accordingly, in view of the above drawbacks, it is a second object of the present invention to provide a wire connector which can facilitate the judging a state whether the mounting or the dismounting of the wire is possible or not, can perform the mounting and the dismounting merely by a pushing manipulation thus enhancing the operational efficiency of the wire connection, and can eliminate the possibility of rupture of constitutional parts.
The prior art and the third task to be solved by the present invention
Further, as another wire connector, for example, as a relay terminal which connects a programmable controller and a large number of electric appliances by way of wires, there has been known a fixing structure of an interface terminal platform which is disclosed in the Japanese Utility Model Registration 3076679. The interface terminal platform is used for connecting the programmable controller with various types of sensors or another interface terminal platform using wires. While the interface terminal platform is connected to the programmable controller through a connector at one side thereof, the interface terminal platform is connected to an inputting/outputting equipment such as a sensor, a motor or the like through a connection portion which is formed of a screw terminal provided to the other side. Here, along with the miniaturization of the control device such as the programmable controller, there has been also a request for the miniaturization of the interface terminal platform.
The relay terminal which constitutes the above-mentioned interface terminal platform has a structure in which an electric connection is established by clamping and fixing the wires using the screw terminal and the terminal fitting. However, a screw head portion of the screw terminal has a diameter greater than a diameter of the wire and hence, when the screw terminal is used for connecting a large number of wires, it is difficult to make a size of the connection portion smaller than the diameter of the above-mentioned screw head. Accordingly, it is difficult to collect the connection portions in high density so that it is difficult to reduce a floor area of the relay terminal.
Further, in arranging the screw terminals in a plurality of rows on a same plane, when the number of rows becomes three or four, it is difficult to pull out the wire of the row positioned in the midst of the rows and hence, such an arrangement cannot be adopted in a practical use. Accordingly, when the screw terminals are arranged in many rows, they cannot be arranged on the same plane and it is necessary to form a stepped portion for every row of the connection portions. As a result, when the connection portions of many rows are adopted, that is, when the number of rows is three or four, a height size of the terminals is increased in proportion to the number of rows and hence, the miniaturization cannot be achieved.
Further, with respect to a terminal fitting in the inside of the housing, one end of the terminal fitting is directly connected or bonded to a printed circuit board and the other end of the terminal fitting is engaged with the screw terminal. Accordingly, when the stepped portion is provided for every row, it is necessary to prepare terminal fittings which differ in height. As a result, when it is required to form the connection portions in a plurality of rows, for example, three rows or four rows, it is necessary to prepare the terminal fittings which differ in height size and this has been a cause to increase kinds of parts to be produced and administrated and to push up a cost.
The third object of the present invention is, in view of the above-mentioned drawback, to provide a miniaturized small wire connector which can connect a large number of wires using a small number of parts and at a low cost.